add openbeacon-compatible crc (CCITT-16)
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@ -8,7 +8,7 @@ OBJS = main.o
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VPATH +=
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OBJS +=
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OBJS += basic/basic.o basic/reinvoke_isp.o basic/delayms.o basic/voltage.o
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OBJS += basic/keyin.o basic/uuid.o
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OBJS += basic/keyin.o basic/uuid.o basic/crc.o
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LIBS += core/libcore.a lcd/liblcd.a applications/libapp.a filesystem/libfat.a usb/libusb.a funk/libfunk.a
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##########################################################################
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@ -106,3 +106,4 @@ $(OUTFILE).elf: $(OBJS) $(SYS_OBJS) $(LIBS) $(LPCFIX) $(LD_TEMP)
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.PHONY: $(LD_TEMP) lcd/liblcd.a applications/libapp.a filesystem/libfat.a usb/libusb.a
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@ -152,4 +152,8 @@ uint16_t GetUUID16(void);
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// for core/iap/iap.c (no official definition)
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void iap_entry(uint32_t param_tab[], uint32_t result_tab[]);
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// crc.c
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uint16_t crc16(char * buf, int len);
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#endif
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@ -0,0 +1,24 @@
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#include "basic.h"
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// Calculate the CRC for transmitted and received data using
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// the CCITT 16bit algorithm (X^16 + X^12 + X^5 + 1).
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uint16_t crc16(char * buf, int len){
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unsigned int crc=0xffff;
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for(int i=0;i<len;i++){
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crc = (unsigned char)(crc >> 8) | (crc << 8);
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crc ^= buf[i];
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crc ^= (unsigned char)(crc & 0xff) >> 4;
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crc ^= (crc << 8) << 4;
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crc ^= ((crc & 0xff) << 4) << 1;
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};
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return crc;
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};
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/* Note:
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It is best not to alter this code. For example, (crc<<8)<<4 does
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not generate the same code as crc<<12. Although the result of the
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computation is the same, the latter generates much more code and
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executes slower.
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*/
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